Apparatus for reducing the dynamic pressure of combustion air at the burner head of an oil burning appliance

ABSTRACT

A method and apparatus for reducing the dynamic pressure of combustion air at a burner head of an oil fired appliance are disclosed comprising means for changing the direction of flow of at least a part of the combustion air, during its passage from a combustion air blower to the burner head.

iliiited States Patent Palm et a1. Nov. 11, 1975 APPARATUS FOR REDUCING THE [56] References Cited DYNAMIC PRESSURE OF COMBUSTION ED STATES PATENTS AIR AT THE BURNER HEAD OF AN OIL 2,090.567 8/1937 Andler 239/470 X BURNING APPLIANCE 7 2,095,230 12/1937 Camerino 415/209 2,214,246 9/1940 Finnigan 239/402.5 [75] Inventors it 2311 52 9 l f Ivar 2,433,317 12/1947 Carter 431/265 2,738,836 3/1956 Monastesse 431/265 Chnster ,Gustavsson of 2,895,293 7/1959 Hodge 431/s-x Norrkopmg, Sweden 3,166,394 l/l965 Lockwood 415/209 73 Assigneez Bjorn 01 Magnus Palm, 3,227,202 l/1966 Morgan 431/9 X Norrkoping Sweden 3.306.336 2/1967 Zenkner 431/265 X [22] Filed: Jan- 24, 19 3 Primary E.\ami11er"-Char1es J. Myhre Assistant E.\'aminerWiI1iam C. Anderson 21 A1.N.:32,4 i 1 PP O 6 3 0 Alto/716), Agent, or FirmHo1man & Stern [30] Foreign Application Priority Data [57] ABSTRACT Mar. 14. 1972 Sweden 3232/72 A method and apparatus for reducing the dynamic pressure of combustion air at a burner head of an oil [52] US. Cl. 431/182, 239/402, 44331l/128655, fired appliance are disclosed Comprising means for [51 1 Int Cl F23M g changing the direction of flow of at least a part of the Field of Search u 431/8, 9 182, 185 combustion air, during 1ts passage from a combustion air blower to the burner head.

2 Claims, 13 Drawing Figures US. Patent Nov. 11, 1975 Sheet 2 of5 3,918,885

FIGA.

US. Patent N0v.1l, 1975 Sheet30f5 3,918,885

US. Patent Nov.l1, 1975 Sheet5of5 3,918,885

PRESSURE OF COMBUSTION AIR AT THE BURNER HEAD OF AN OIL BURNING APPLIANCE BACKGROUND OF THE INVENTION In oil'burning appliances it is desirable to reduce the dynamic pressure while maintaining the static pressure of the combustion air at the burner head, so that the flame burns evenly without the tendency to be blown out at reduced rates of oil feed, and to overcome the excess pressure arising in the boiler and flues.

In order to achieve this, it has been proposed to reduce the width of the air supplying blower to give the blower the desired static as well as dynamic pressure. This, however, has proved less advantageous, since for reasons of standardization it is desirable to be able to use the same blower and blower casing for different sizes of appliance.

SUMMARY OF THE INVENTION The present invention provides a method of reducing the dynamic pressure of combustion air at the burner head of an oil burning appliance wherein at least part of the air is caused to change its direction of flow whilst passing from a blower to the burner head.

The invention further provides an apparatus for reducing the dynamic pressure of combustion air at a burner head of an oil-fired appliance comprising means for changing the direction of flow of at least a part of the combustion air during its passage from a blower to the burner head.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example with reference to the accompanying drawings, wherein:

FIGS. 1 5 show diagrammatically five different embodiments of an oil burning appliance equipped with an apparatus according to the invention;

FIG. 6 shows a section view taken along the lines VIVI in FIG. 7 of a sixth form ofan appliance with an apparatus according to the invention,

FIG. 7 shows a view of the appliance as shown in FIG. 6 from the side of the burner head;

FIGS. 8 and 9 show diagrammtically two further embodiments of an oil burning appliance, provided with an apparatus according to the invention;

FIG. 10 shows a partial section view taken along the line XX in FIG. 1 1 of the apparatus according to the invention intended to be fitted into conventional oil burner appliances; and

FIG. 11 shows a view of the arrangement as shown in FIG. 10 from the burner head.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, an impeller wheel 18 is mounted in a spiral casing 1 which is connected straight to an air supply pipe 3 leading to a burner head 2. Into the air supply pipe 3 are fitted two longitudinal baffles or partitions 4, 5, which are parallel to each other and parallel to the longitudinal axis of the air supply pipe 3. The partitions 4, 5 are connected to the walls 6 of the air supply pipe 3 each by a supporting member 7, obliquely mounted so as to produce a zig-zag-shaped channel for the combustion air by making this turn through 180 round the free edges of the opposed baffles.

This form of appliance shown in FIG. 2 differs from that shown in FIG. 1 in that the baffles 8, 9 are mutually parallel and obliquely positioned so as to form acute angles with the central axis of theair supply pipe 3.

In FIG. 3, a blower 18 is so mounted in a spiral casing 1 as to produce an air passage 19 alongside the blower 18. A port 20 is provided in the wall 21 of the blower casing, which restricts the air passage 19 to the air supply pipe 3 leading to the burner head 2.

In the air supply pipe 3 there is provided a baffle 5 which projects from a rear wall 22 and extends past the port 20. A transverse wall 7, which is spaced from the free end of the baffle 5, projects from the wall of the impeller casing 21, and terminates short of the wall 6 of the air supply pipe 3 lying opposite the wall 21 of the blower casing. Another baffle 4 extends from the free end of the transverse wall 7 in the direction opposite to that of the baffle 5 and terminates at a distance from the rear wall 22 of the air supply pipe 3. The two baffles 4, 5 are so located in the air supply pipe 3 that their longitudinal edges are connected to the wall 6 of the air supply conduit 3 along generating lines, and that the cross-sectional areas of the passages formed between the two baffles 4, 5, between the baffle 5 and the wall 21 of the blower-casing, and between the baffle 4 and the wall 6 of the air supply pipe 3 are substantially equal to each other and substantially equal to the port aperture 20 and to the apertures between the free ends of the baffles 4, 5 and the transverse wall 7 or the rear wall 22 of the air supply pipe.

In FIG. 4, the air supply conduit 3 is provided with at least two transverse, inwardly directed baffles 10 with central openings 12 and at least two central baffles 11, one central baffle 11 being located behind each of the openings 12.

The openings 12 are preferably of a size such that their free area is between one quarter and one half of the cross-sectional area of the air supply conduit 3.

In FIG. 5, an outlet pipe 3, extending tangentially from the blower casing 1, is provided with a end wall 22, spaced from the impeller casing 1. An air supply pipe 13, leading concentrically to the burner head 2 and having a cross-sectional area which is a half of that of the outlet pipe 3, has its inlet end spaced from the end wall 22, whereby the air is made to turn through round said inlet end.

In FIGS. 6 and 7, a casing 1 of a radial blower in an oil burning appliance is provided on oneside with central air intake opening 14 and a substantially horizontal casing edge 15, located on the underside of the casing l, as well as with an outlet port 16, directed substantially tangentially and preferably at 45 to the edge 15, and leading to a short, substantially horizontal passage 17 of preferably rectangular cross section, arranged under the edge 15.

The wall of the passage 17 facing the air-intake side is provided with a preferably rectangular port 20, which opens out tangentially into an air supply pipe 3, located beside the blower casing 1 and straight under its air-intake port 14, the air in the air supply pipe being thus made to move helically and axially in a direction opposite to that of the passage 17. This axial reversal of the air flow through 180 entails a considerable reduction in the dynamic pressure, to which the helical movement also contributes.

In addition, the positioning of the air supply pipe 3 on the side of the impeller casing 1 and directly beneath its air intake 14 has the consequence of making the total structural height of the appliance considerably less than when the air supply pipe lies wholly underneath the blower casing as has hitherto been common. This decreased height has proved particularly advantageous in, connection with the noncustomary, low heating boilers, where conventional burner appliances have encountered spaced difficulties.

It has proved of advantage to provide in the air supply pipe 3, within the port aperature 20, a cylindrical rotary draught valve, which is not shown but is known as such, for controlling the blower capacity according to the burner capacity.

In FIG. 8, the air supply conduit 3 has two turbines 23, 24, whose vanes 25, 26 are inclined in opposite directions.

The trailing turbine 24 may advantageously be followed by a wreath of radial, axially parallel, plane guides, not shown.

In another embodiment at least one and preferably several baffles 10, (see FIG. 9) which are equi-spaced and have circular central openings 12, are arranged projecting from the pipe wall 6 in an air supply pipe 3 leading from a blower 1 to a burner head 2. The diameter of the openings 12 may advantageously be from a quarter to a half, and preferably a third, of the diameter of the pipe 3, and the distance between adjacent baffles is at least equal to the radius of the opening 12.

In this arrangement an annular air swirl 27 is formed behind each baffle 10, causing a decrease in the dynamic air pressure.

Referring now to FIGS. 10 and 11, in the air supply pipe 3 of an oil burning appliance there is provided an insert 28 of sheet metal, which from the blower end consists of a first cylindrical part 29, arranged to bear against the inside of the air supply pipe 3, this part 29 being connected to a funnel-shaped part 30 and another cylindrical part 31 extending from the smaller end of part 30.

The funnel-shaped part 30 is provided with a series of slots 32, at right angles to its generating lines and evenly distributed over its perimeter. The edges of the slots 32 facing the larger end of the funnel-shaped part 30 are formed as baffles 33, bent inwardly towards the 4 center and advantageously forming an angle of about 30 with the outside surface of the part 30.

Air stream passing through the slots 32 are caused to flow in directions substantially opposite to that of the stream passing through the other cylindrical part 31, and in this way the dynamic pressure of the resultant air stream is reduced.

It has proved advantageous to arrange the slots 32 in at least three groups divided by unslotted portions 35, and to provide radial guides 34 between the inner surface of the air supply pipe 3 and the outer surface of the insert 28, on the one hand, and within the other cylindrical part 31, preferably in the middle of the unslotted portions 8, on the other.

Although nine embodiments of the invention have been shown and described above, other embodiments are possible within the scope of the invention.

We claim:

1. An apparatus for reducing the dynamic pressure of combustion air at a burner head of an oil-fired appliance, said apparatus comprising in combination:

a blower made in the form of a radial impeller and having a casing;

an air supply pipe;

said casing having an air-intake opening and a flowdiverting edge disposed on the underside thereof, said casing having an outlet port disposed substantially tangentially to said edge and extending into a horizontal passage disposed under said edge;

said horizontal passage having a side wall with a second port disposed therein, said second port opening tangentially into said air supply pipe, said air supply pipe extending in a direction perpendicular to said horizontal passage and extending toward said burner head; and

said side wall being disposed to the side of said casing and directly below said air-intake opening of said casing, thereby changing the direction of flow of at least part of the combustion air during its passage from said blower to said burner head and thus reducing its dynamic pressure.

2. An apparatus as claimed in claim 1, wherein a cylindrical rotor draught valve is disposed within said second port opening tangentially into said air supply pipe. 

1. An apparatus for reducing the dynamic pressure of combustion air at a burner head of an oil-fired appliance, said apparatus comprising in combination: a blower made in the form of a radial impeller and having a casing; an air supply pipe; said casing having an air-intake opening and a flow-diverting edge disposed on the underside thereof, said casing having an outlet port disposed substantially tangentially to said edge and extending into a horizontal passage disposed under said edge; said horizontal passage having a side wall with a second port disposed therein, said second port opening tangentially into said air supply pipe, said air supply pipe extending in a direction perpendicular to said horizontal passage and extending toward said burner head; and said side wall being disposed to the side of said casing and directly below said air-intake opening of said casing, thereby changing the direction of flow of at least part of the combustion air during its passage from said blower to said burner head and thus reducing its dynamic pressure.
 2. An apparatus as claimed in claim 1, wherein a cylindrical rotor draught valve is disposed Within said second port opening tangentially into said air supply pipe. 